Railway signaling apparatus



Nov. 26, 1935; A, L VENCILL 2,021,951

RAILWAY S I GNALI NG I APPARATUS Filed Dec. 19, 1935 Permanent MagnezFig.1.

JTIVIHVYTIR I Patented Nov. 26, 1935 UNITED STATES RAILWAY SIGNALINGAPPARATUS Albert L. Venoill, Pittsburgh, Pa., assignor to The 7 UnionSwitch & Signal Company, Swissvale, Pa. a corporation of PennsylvaniaApplication December 19, 1033, Serial No. 703,075

9 Claims.

My invention relates to railway signaling apparatus of the typeinvolving track circuits, and has for an object the provision, inapparatus of this type, of a track circuit including a relay 5 whichwill respond in one way to the decrease in current supplied to it when atrain enters the associated section and in another way to the increasein current supplied to it when the train leaves the section, but whichwill not be affected 10 by steady value of the track circuit current orto gradual changes in the current supplied to the relay due for exampleto changes in ballast conditions.

I will describe two forms of apparatus eml5 bodying my invention, andwill then point out the novel features thereof in claims.

In the accompanying drawing, Fig. l is a diagrammatic view showing oneform of apparatus embodying my invention. Fig. 2 is a view show- 20 inga modification of a portion of the apparatus shown in Fig. 1 and alsoembodying my invention.

Similar reference characters refer to similar parts in each of theviews.

25 Referring first to Fig. 1, the reference characters l and I designatethe track rails of a stretch of railway track along which trafficnormally moves in the direction indicated by the arrow. These rails aredivided by insulated joints 30 2 to form a plurality of track sections,of which only one complete section,'DE is shown in the drawing. Traflicmoving through section DE from left to right is governed by a signal S,which, as'here shown, is a light signal comprising 35 a proceed lamp G,a caution lamp Y, and a stop lamp R.

Section DE is provided with a track circuit comprising a battery Hconnected across the rails at the exit end of the section, as well asthe pri- 40 mary 6 of a transformer T and the Winding of a relay Fconnected in series across the rails at the entering end of the section.The secondaryv l of the transformer T is connected with the operatingwinding of a relay A.

45 Relay A is a polarized relay comprising a U- shaped core 3, which iseither a permanent magnet or is permanently magnetized by means exteriorto the core. Pivotally mounted at 4 in the back strap of the core 3is'an armature 4,

50 which is arranged to oscillate between the two pole faces of thecore, and which carries a winding 5 which receives energy from thesecondary j l of the transformer T. The armature 4 cooperates with pairsof contacts 8, 9 and i in such 55 manner that contacts Band 9 are closedWhenv the armature 4 is swung to the right, which I will term its normalposition, and contact I0 is closed when this armatureis swung to theleft or reverse position.

The relay F may be a neutral relay. Associated-with the relays A and Fis a third relay K, which is a distant relay controlled by the followingcircuit: From terminal B of a suitable source of current at location E,through front contact I4 of relay F at location E, normal 10 contact 9of relay A at location E, and winding of relay K, to terminal C of thesame source of current.

The proceed lamp G is provided with a circuit which passes from terminalB, through normal contact 8 of relay A, front contact ll of relay F,front point of contact l3 of relay K, and lamp G to terminal 0 of thesame source of current. The caution lamp Y is provided with a circuitWhich passes from terminal B, through normal contact 8 of relay A, frontcontact ll of relay F, back point of contact l3 of relay K, and lamp Yto terminal C. The stop lamp R is provided with two circuits. One ofthem is from terminal B, through the reverse contact In of relay 'A, andlamp R to terminal C. The other is from terminal B, through back contactI2 of relay F and lamp R to terminal 0.

The operation of the system is as follows: When section DE isunoccupied, armature 4 of relay A isin the normal position, as shown inthe drawing, and relay F is energized by current from battery II. If thesection next in advance is also unoccupied, relay K is energized. Lamp Gwill then be lighted, so that signal S will indicate proceed. If,however, the section in advance of point E is occupied by a train, relayK will be deenergized, so that lamp Y will be lighted and signal S willindicate caution.

I will now assume that a train enters section 40 DE. When this occurs,the shunt afforded by the wheels and axles of such train will suddenlyreduce the amount of current flowing in primary 6 of transformer T, andthis sudden change in the primary current will induce an impulse ofcurrent in secondary l of such polarityas to reverse the position ofarmature 4. This armature will then remain in its reverse position,because relay A is characterized by the fact that when it becomesdeenergizcd, the armature remains in the position corresponding to thepolarity of the current with which the relay was last energized. Inother words, relay A is what is known as a last position relay. If theshunt afforded by the wheels and axles of the train is suflicientlyeffective, the current supplied torelay F will be reduced to less thanthe release value of this relay, and this relay will accordingly operateto open its front contacts and close its back contacts but if thecurrent supplied to primary winding 6 and the winding of relay F is notreduced to the release point of relay F, the latter relay will remainenergized. In either event the circuits for the proceed lamp G andcaution lamp Y will be opened at contact 8 of relay A, and if relay Freleases they will also be opened at contact ll of this relay; the firstcircuit for stop lamp R will be closed at contact ill of relay A and ifrelay F releases the second circuit for lamp R will be closed at backcontact i2 of this relay. Signal S will then indicate stop.

When the train leaves section D--E, there will be a sudden increase inthe amount of current supplied to primary 6 of transformer T and thissudden change in the primary current will cause an impulse to be inducedin secondary I of such polarity as to return the armature 4 to itsnormal or right-hand position. This armature will thereafter remain inits normal position until the relay again becomes energized by animpulse of reverse polarity. If relay F was deenergized while the trainwas in the section, this relay will again become energized. Relay K willhave become deenergized due to the train entering the section in advanceof section DE, and so signal S will indicate caution until the trainpasses out of such section in advance, when it will again indicateproceed.

The operation of relay A is independent of the energy level at theleft-hand end of the section D--E, and is dependent only on the changein the amount of current supplied to transformer T when a train entersor leaves the section. It follows that changes in the characteristics ofthe track circuit due to variations in weather or other conditions willnot affect the operation of this relay. During dry weather conditionswhen very good shunting action is necessary to cause relay F to releasein response to a train entering the section, relay A will be reversed bya relatively poor shunt because of the relatively large change in theamount of current supplied to this relay as the train enters thesection; whereas during wet weather conditions when relay A may not beso sensitive, relay F will be released by a relatively poor shunt. Thecombination of the two relays A and F provides, therefore, forreliableshunting under all possible conditions of the track.

If desired, relay F may be connected in multiple with the primary 6 oftransformer T, as shown in Fig. 2, and a condenser .l5 may then beincluded in series with primary 6 to prevent saturation of the core oftransformer T by direct current from the battery H.

Although I have herein shown and described only two forms of apparatusembodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a section of railway track, a source of currentconnected across the rails at one point in said section, means receivingenergy from said rails at another point in said section and selectivelyresponsive to the changes in the value of the current received therebydue to the entrance of a train into the section and the exit of a trainfrom the section, a relay also receiving energy from the rails of saidsection and arranged to be effectively energized or not according as theamount of energy which it receives is above or below a given value, anda signal associated with said section and controlled jointly by saidmeans and said relay in such manner as to provide a proceed indicationwhen and only when said means has responded to the exit of a train fromthe section and said relay is effectively energized.

2. In combination, a section of railway track, a source of directcurrent connected across the rails of said-section, a transformer theprimary of which receives energy from said rails, a relay receivingenergy from the secondary of said transformer and selectively responsiveto momentary impulses of one polarity or the other due to decrease orincrease of the current supplied to the primary of said transformer, asecond relay receiving energy from the rails of said section andarranged to be effectively energized or not according as the amount ofenergy which it receives is above or below a given value, and a signalassociated with said section and controlled jointly by said two relaysin such manner as to provide a proceed indication when and only when thefirst relay has responded to an impulse of said otherpolarity and saidsecond relay is effectively energized.

3. In combination, a section of railway track, a source of directcurrent connected across the rails of said section, a transformer theprimary of which receives energy from said rails, a relay receivingenergy from the secondary of said transformer and having a polararmature which moves to a normal or a reverse position in response tomomentary impulses of normal or reverse polarity due to increase ordecrease of the current supplied to the primary of the transformer andwhich remains in the position to which it was last moved untilinfluenced by an impulse of the other polarity, a second relay receivingenergy from the rails of. said section and arranged to be efiectivelyenergized or not according as the amount of energy which it receives isabove or below a given value, a signal for said section, and means forcausing said signal to indicate proceed when and only when said polararmature is in its normal position and said second relay is energized.

4. In combination, a section of railway track, a source of directcurrent connected across the rails of said section, a transformer theprimary of which receives energy from said rails, a relay receivingenergy from the secondary of said transformer and having a polararmature which moves to a normal or a reverse position in response tomomentary impulses of normal or reverse polarity due to increase ordecrease of the current supplied to the primary of the transformer andwhich remains in the position to which it was last moved untilinfluenced by an impulse of the other polarity, a second relay receivingenergy from the rails of said section and arranged to be effectivelyenergized or not according as the amount of energy which it receives isabove or below a given value, a signal for said section, a proceedcircuit for said signal closed only when said polar armature is in itsnormal position and said second relay is energized, and two stopcircuits for said signal one of which is closed when said polar armatureis in its reverse position and the other of which is closed when saidsecond relay is deenergized.

5. In combination, a section of railway track, a

source of direct current connected across the rails of said section, atransformer the primary of which receives energy from said rails, arelay receiving energy from the secondary of said transformer andselectively responsive to momentary impulses of one polarity or theother due to decrease or increase of the current supplied to the theprimary of. said transformer, a second relay having its operatingwinding interposed between said transformer primary and one of the trackrails and arranged to be effectively energized or not according as theamount of energy which it receives is above or below a given value, anda signal associated with said section and controlled jointly by said tworelays in such manner as to provide a proceed indication when and onlywhen the first relay has responded to an impulse of said other polarityand said second relay is effectively energized.

6. In combination, a section of railway track, a source of directcurrent connected across the rails of said section, a transformer theprimary of which receives energy from said rails, a relay receivingenergy from the secondary of said transformer and selectively responsiveto momentary impulses of one polarity or the other due to decrease orincrease of the current supplied to the primary of. said transformer, acondenser interposed between the primary of said transformer and one ofthe track rails to prevent the flow of steady direct current in thetransformer primary, a second relay having its operating windingconnected across the rails of said section and arranged to beefiectively energized or not according as the amount of energy which itreceives is above or below a given value, and signaling apparatusassociated with said section and controlled jointly by said two relays.

7. In combination, two successive sections of railway track, a source ofdirect current connected across the rails of each section, a transformerfor each section the primary of which receives energy from the rails ofthe section, a relay for each section receiving energy from thesecondary of. the associated section and each having a polar armaturewhich moves to a normal or a reverse position in response to momentaryimpulses of normal or reverse polarity due to increase or decrease ofthe current supplied to the primary of the transformer and which remainsin the position to which it was last moved until influenced by animpulse of the other polarity, a second relay for each section receivingenergy from the rails of the section and arranged to be effectivelyenergized or not according as the amount of energy which it receives isabove or below a given value, a third relay for the rear section, meansfor energizing said third relay if and only if the armature of the firstrelay for the forward section is in its normal position and the secondrelay for the forward section is energized, a signal for the rearsection, and means for causing said signal to indicate proceed if andonly if the armature of the first relay for the rear section is in itsnormal position and the second relay for the rear section is energizedand said third relay is energized.

8. In combination, a section of railway track, a source of currentconnected across the rails of said section, means including a contactcontrolled by energy received from said rails in such manner as to openupon a rapid decrease in the energy received by said means occurringwhen a train enters said section and to remain closed if the energyreceived by said means changes gradually, a relay receiving energy fromsaid rails and arranged to be effectively energized or not according asthe amount of energy which it receives is above or below a give value, asignal for said section, and means for causing said signal to indicateproceed when and only when said contact is closed and said relay isenergized.

9. In combination, a section of. railway track, a source of currentconnected across the rails of said section, means including a contactcontrolled by energy received from said rails in such manner as to openupon a rapid decrease in the energy received by said means occurringwhen a train enters said section and to remain closed if the energyreceived by said means changes gradually, a relay receiving energy fromsaid rails and arranged to be.

